docs: def md(filename):
      '''
      Load .md (markdown) file and sanitize it for PyPI.
      Remove unsupported github tags:
       - code-block directive
       - travis ci build badges
      '''
      content = io.open(filename).read()
  
      for match in RE_BADGE.finditer(content):
          if match.group('badge') not in BADGES_TO_KEEP:
              content = content.replace(match.group(0), '')
      return content